Knuckle coupler assemblies are well known in the railway industry to attach one railroad car to another. Each railroad car to be connected to another railroad car has a coupler. The two couplers of adjacent railroad cars that are about to be coupled each have a knuckle attached to them. When the couplers go together and become coupled, the knuckles snap closed. Thus, you have two couplers, two knuckles, and two thereby formed apertures for the knuckle pins to slip into. A railroad pin is inserted into the through apertures of the knuckles to lock shut the knuckles and secure the connection between the two railcars. However, over time, the alignment of the apertures formed by the connection of the two knuckles and coupler bodies are difficult to attain because of metal wear. Misalignment of the apertures of the knuckle and coupler body reduces the area size of the overall aperture for receiving the railroad pivot pin, making installation of the pin more difficult and potentially hazardous to the railroad worker during connection of the railroad cars.
In addition, cotter pins have been previously used to hold the pivot pin within the aperture of the railroad car coupler. The continued motion of the railroad cars can wear into a specific area of the pin which can cause fatigue and breakage of the cotter pin material.
Another disadvantage of using a cotter pin to secure the pivot pin within the railroad coupler is that installing or removing the cotter pin can be difficult and dangerous to the railroad worker.